Peter Hamby is a national political reporter at CNN and the author of the recent Joan Shorenstein Center report “Did Twitter Kill the Boys on the Bus? Searching for a Better Way to Cover a Campaign.”

By now, everyone knows that Mitt Romney’s inner circle was righteously peeved at New Jersey Gov. Chris Christie for spending the final days of the 2012 presidential race arm-in-arm with President Obama as they toured the Jersey coastline after its thrashing by Hurricane Sandy. The buddy-buddy act boxed Romney out of national media coverage for days while lending the president some bipartisan street cred.

But it wasn’t just the storm. Christie had rankled Romney’s team throughout the campaign: He held back his endorsement as long as possible, flirted with big-shot GOP donors who begged him to jump into the race and used his prime-time address at the Republican National Convention to puff up his Garden State record — without mentioning Romney once.

For Romney’s aides, dealing with Christie’s overbearing team was about as pleasurable as a traffic jam on the New Jersey Turnpike. For Christie’s staff in Trenton, the feeling toward the Romney machine was pretty much mutual.

Many months after Romney’s loss, that toxic relationship is revealed in page-turning detail in “Double Down,” a chronicle of last year’s grind-it-out election by journalists Mark Halperin and John Heilemann. The authors deploy the conversation-driving formula that propelled their previous book, “Game Change: Obama and the Clintons, McCain and Palin, and the Race of a Lifetime,” to bestseller status and a movie deal with HBO. (The same network has already optioned the rights to “Double Down.”) The duo’s M.O. — translating insider politics for mass-market readers with behind-the-scenes reporting and Gonzo flair — is custom-built for today’s news cycle, in which scoops explode on Twitter and oblige the rest of the political media to chase, confirm, refute, scrutinize, analyze to death. The digital blast radius for “Double Down” is infinite.

“Double Down: Game Change 2012” by Mark Halperin and John Heilemann (Penguin Press). (Penguin Press)

And it will hit Christie first. Halperin and Heilemann make abundant use of a vice-presidential vetting file dropped into their hands by someone in Romney’s orbit to illuminate secrets about the governor. Delivering the documents to the authors was a stunning breach of political decorum that can only be read as a giant middle finger at Christie and his aides.

According to the authors, Romney and his team were shaken by what they discovered about Christie during “Project Goldfish,” as the hush-hush veep search process was known. His “disturbing” research file is littered with “garish controversies,” the authors write: a Justice Department investigation into his free-spending ways as U.S. attorney, his habit of steering government contracts to friends and political allies, a defamation lawsuit that emerged during a 1994 run for local office, a politically problematic lobbying career that included work on behalf of a financial firm that employed Bernie Madoff. And that’s not to mention the Romney team’s anxiety about the governor’s girth.

For Christie, who is coasting to reelection on Tuesday and already laying behind-the-scenes groundwork for a 2016 presidential bid, the book’s revelations are a Drudge-ready public relations nightmare that will send his advisers scrambling to explain awkward aspects of his record and his personal life just as he is stepping onto the national stage.

For Halperin and Heilemann (and their publisher), this means one thing: mission accomplished.

Coming off the history-making spectacle of the 2008 race, the borderline­ nihilistic presidential campaign of 2012 presents a challenge to authors seeking to spin a compelling tale. That may explain why the pair devotes considerable attention to the Republican primary contest, a more topsy-turvy drama than the trench warfare between Obama and Romney.

The book lacks the made-for-Hollywood scenes of “Game Change”: Elizabeth Edwards ripping off her shirt to reveal her mastectomy scars in an emotional tarmac confrontation with her cheating husband, or anything Palin-related. But there’s still click-bait aplenty: Obama meditating on drone strikes and telling his aides that he’s “really good at killing people”; Christie’s raging temper; Romney adviser Stuart Stevens vomiting backstage after Clint Eastwood’s performance art in Tampa; Romney’s fascination with fat people, including his habit of ribbing male campaign staffers about dating overweight women; George W. Bush calling Rick Perry, his gubernatorial successor in Texas, “a chicken-[expletive] guy”; Obama’s team secretly polling and focus-grouping the notion of replacing Joe Biden with Hillary Rodham Clinton on the Democratic ticket; and so on. It’s a book that will launch a thousand listicles.

Such goodies were mined over three years from deep-background interviews with the candidates, their aides and the small galaxy of Washington fixers who surrounded the campaigns. The authors explain their hazy sourcing in a note at the book’s conclusion; media snobs will have a field day. The Halperin-Heilemann method, a number of those who sat for interviews told me, is to invite a subject to a private room at a restaurant or a plush hotel suite, ply them with booze and let the stories flow. But the alcohol was unnecessary; the wild success of the first volume guaranteed that insiders would talk this time. Indeed, in a summer’s worth of casual conversations with veterans of all the campaigns, it was difficult for me to find anyone who didn’t consent to an interview with the pair.

The book’s loose argument is that both Obama and Romney placed their bets about the race early on and “doubled down” throughout the contest. It’s an apt take on Obama World. The “Obamans,” as the authors call them, set out to annihilate Romney almost two years before the election and executed their plan with brutal efficiency. There were hiccups along the way, specifically Obama’s dreary debate-prep sessions and his cringe-worthy performance in Denver, but his deputies in Chicago rarely deviated from their search-and-destroy mission. Romney’s campaign, though, with its bad habit of reacting to news cycles with snap decisions, always felt more ad hoc, with tactics trumping strategy.

Though the gossip merchants of This Town might be disappointed, readers are for the most part spared staff-level infighting and post-campaign score settling. There are exceptions: Former White House chief of staff Bill Daley comes in for rough treatment, depicted as a feckless outsider lost in the youthful, clannish and data-reliant Obama-verse. Although Romney’s chief strategist, Stevens — a popular punching bag for know-it-all Republican consultants after the loss — emerges mostly unscathed, we witness some flashes of impetuousness. He was frustrated, it seems, to be the lone voice on Team Romney lobbying for Christie to be on the ticket instead of Paul Ryan, who is as much a cipher in the book as he was during the campaign: rarely mentioned and barely consequential.

The authors’ main project is to get into the minds of the candidates, even if the book does little to alter our understanding of the campaign’s main players. Obama is brilliant but peevish, allergic to the nitty-gritty of politics. Romney is a decent man but hopelessly ham-fisted on the stump and oblivious to why voters can’t seem to appreciate his private-equity résumé.

As for the vice president, Biden is as Uncle Joe as ever: loyal to Obama and desperate to be in the arena, but prone to gaffes and rhetorical indulgences that give the president and his aides heartburn. Richard Ben Cramer’s “What It Takes” remains the great ur-text of Bidenology. But the “Game Change” guys do dredge up what might be the Bidenest quote of all time: “I don’t understand why everyone’s so mad at me,” he tells a confidante, after endorsing same-sex marriage before the president did. God bless him.

Obama’s evolving relationship with Bill Clinton is one of the more intriguing tales of “Double Down.” Aware that Clinton would be a crucial asset to the campaign, Obama World lured the former president to its side, even agreeing to pay off Hillary Clinton’s 2008 campaign debt in exchange for Bill’s help. The two presidents slowly warmed to each other throughout the race. “He’s luckier than a dog with two d----,” Clinton told his friends of Obama.

The real drama of the 2012 campaign unfolded on the Republican side: the Newt-killing, Perry-on-painkillers, 9-9-9, couple-of-Cadillacs theatrics of the Republican primary. After opening with some 80 pages of Obama portraiture, the authors gorge themselves on the hot mess of the GOP race for the next 200 pages. The most enjoyable action plays out among the “Romneyites” (yes, the authors have an annoying habit of sprinkling their text with gnomic nicknames; let this be the last time Rick Santorum is called “Santo”). The Romney campaign’s methodical destruction of Gingrich, first in Iowa and again in Florida, is detailed, as is Romney’s problematic lurch to the right as he fought off a conservative insurgency fronted by Santorum and his sweater vest.

If Halperin and Heilemann have a bias, it’s toward the candidates who stood a chance of winning — except for their recurring obsession with Donald Trump. Tim Pawlenty’s campaign merits four pages. Ron Paul is an afterthought. Iowa straw poll winner Michelle Bachmann gets five pages, and the most memorable thing we learn is that she gets her hair done at a place called Fantastic Sam’s.

Jon Huntsman is the exception, and the authors’ rendering of him is not pretty. Perhaps most damning for a candidate who professed to be above politics-as-usual, the authors report that the Huntsman campaign was behind two of the cycle’s roughest news hits: peddling dirt to reporters on Mitch Daniels’s wife, Cheri, a warning shot intended to keep the former Indiana governor out of the GOP field; and facilitating Politico’s splashy story about Cain’s apparent extramarital dalliances, a revelation that drove the pizza magnate from the race.

Halperin and Heilemann fixate just as much on the Republicans who never set foot on a debate stage and who handed Romney enough breathing room and financial support to capture the nomination. Christie gets an entire chapter (titled “Big Boy”). Daniels, Haley Barbour and Mike Huckabee all receive more attention than Cain, who once topped the national polls.

The Nate Silver wing of the Internet will almost surely gripe that the book is an example of political journalism’s worst instincts — it’s too dependent on the hunches and agendas of sources rather than hard measures of why Obama won. The authors ascribe colossal import to the tactical decisions and shouting matches inside campaign war rooms, but their dishy portraits often skimp on the larger forces that drove the race, from an improving economy and demographic shifts to Romney’s charisma deficit and the Obama campaign’s superior voter-contact machinery.

Campaigns, though, aren’t just about number-crunching and statistical analysis. Candidates matter. Voters tell pollsters that they make their choices based on issues such as education, health care, taxes and the economy — and they do. But they also care about temperament, empathy, strength, reason, trust and the human side of these strange and wily people who think they’re up to the task of running the country. And as Halperin and Heilemann understand, so do readers.

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Game Change 2012

By Mark Halperin and John Heilemann

Penguin Press. 499 pp. $29.95